Simplified Block Diagram
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- 2 to 4 Li+ Cell Battery-Powered Devices
- Notebook and Subnotebook Computers
- PDAs and Mobile Communicators
Internal 5V and 3.3V linear regulators power the MAX1533/MAX1537 and their gate drivers, as well as external keep-alive loads, up to a total of 100mA. When the main PWM regulators are in regulation, automatic bootstrap switches bypass the internal linear regulators, providing currents up to 200mA from each linear output. An additional 5V to 23V adjustable internal 150mA linear regulator is typically used with a secondary winding to provide a 12V supply.
The MAX1533/MAX1537 include on-board power-up sequencing, a power-good (PGOOD) output, digital soft-start, and internal soft-shutdown output discharge that prevents negative voltages on shutdown. The MAX1533 is available in a 32-pin 5mm x 5mm thin QFN package, and the MAX1537 is available in a 36-pin 6mm x 6mm thin QFN package. The exposed backside pad improves thermal characteristics for demanding linear keep-alive applications.